Process for making cellulose sheets



March 9, `1.943.

E. czAFEKA PROCESS FOR MAKING CELLULOSE SHEETS 2 Sheets-Sheet 1 Filed Aug. 12, 1937 M4 W e V `W Y M h/d S W M\` S 9 p/n L- 0 l l. 4M Q We Z 4 e 5 1, Z. /f/ O o 7 1 .www @e7 PEK :avg Q ATTORNEY March 9, 1943, E. czAPEK 2,313,520

PROCESS FOR MAKING CELLULOSE SHEETS Q Filed Aug. l2, 1937 2 Sheets-Sheet 2 INVENTOR ATTORNEY coagulation liquid.

PatentedMar. 9, 1943 UNITED ASTATI-'11S PATENT OFFICE PROCESS Foa MAKING cELLULosE SHEETS Emil Czapek, New York. N. Y. Appueeuon August 12, 1937, serial No. 158,741

i (C1. 11s- 51) 10 Claims.

This invention relatesv to the' production of improved cellulose sheets. films or the 1ike,as new articles of manufacture, the processes of making the same and the machines or devices for carrying out such processes.

Among the objects ofthe present invention,'

it is aimed te provide en improved cellulose sheet, lm or the like of an exceedingly uniform.

become sulciently solidified so that it cannot be stretched and deformedthereafter. This constitutes an important step in the-present invention,- since it has been found in practice that, espei' desired to produce layers of cially when it is exceedingly slight thickness, they cannot bereadily detached from a supporting surface Without deforming or impairing the same by the' forces resulting .from the tension of the lm layerA in the ensuing baths.

It is still anotherobject of the present invention to provide an'improved cellulose sheet, hn or the like of an exceedingly slight thickness as an instance having a weight per thousand square -inches of less than 0.40 ounce without striations and the like and having a width of forty inches or more by means of a continuously operating process.

It is still another object of the present invention to provide an improved cellulose sheet, nlm l or the like of unusual thickness with an exceedingly uniform physical structure throughout.

It is still another object of the present invention to provide improved processes for producing the aforesaid improved cellulose sheets, films and the like and to provide improved devices for carrying out such processes.

These and other features, capabilities and advantages of the invention will appear from the 'subjoined detaildescription of specic embodiments including the article, processes for making the article. and machines fo'r carrying out the processes illustrated in the accompanying drawings in which l Figure 1 is a section of one embodiment more or less diagrammatically's'hown;

Fig. 2 is a sectionof another embodiment more or less diagrammatically shown;

Fig. 3 is a fragmental end elevation of a stripping device used in these'embodiments; and l Fig. 4 is a fragmental section of the stripping device shown in Fig. 3.

To carry out this invention a pouring base is used upon which a cellulose solution in the form of a layer is spread. The layer becomes solidified .as the result'of` immersing the base into a The essential novelty and the advancement achieved resides in the fact that not only is the coagulation of the layer carri-ed out on the base but a part of the subsequent regeneration of the coagulated strip is also so carried out on the base and, at least, long enough so that the strip will 45 set forth..

In order to eliminate such deleterious effects on the film, this invention aims to provide a device which enables introducing a coagulation solutionunder the strip and to wet the base during the process reaction. When the coagulation treatment is so controlledthat the layer is detached from the original'supporting base bythe moistened edge of a stripping device and guided over` said device while the inner face fof the layer is thereby Amoistened by theI coagulating liquid and is again returned to the base, thenf the layer will solidify into a self-sustaining condition )while effectively supported and. is thereby protected against being stretched,` extended 'or shrunkuntil it has sufli-` ciently solidied into a self -sustaining condition where it can n longer be objectionably stretched, extended or shrunk by the aforementioned forces.

" In thev process, constituting the invention in.

part, a thick liquid I of cellulose solution, for instance viscose,l is spread uponv thegsurface 2 of apouring base 3 by means of a pouring device 4. By moving or rotating the pouring base 3 the so spread cellulose coagulation liquid 6 or trough 1.

The character of the liquid 6 depends upon the cellulose solution being used. For viscose a "sulo' phuric acid bath with a supplementary agent of sodium, ammonia, or a similar sulphate is chosen as the coagulation and 'regeneration liquid. The

strength of the'solution must be chosen to correspond to the eiect desired as is hereinafter In accordance with the present invention, the coagulation of the-layer 5 starts while the layer passes the point 8 on the surfacel -layer 5 on the base enters the coagulation bath. The velocity of the movement of the base 3 and the concentration of the liquid 6 is of such a character, that the coagulation is vcompleted before it 'passes the point indicated as 9 in Fig.' l.

After the layer 5 is coagulated to a strip which is still soft and delicate, the regener to aid in the'regeneratiox'ly layer 45 passes into a suitable provided in the containerl 2 where the ation ofthe above the level Fig. las exemplifying one embodiment of the strip and its solidiflcation begins. After this coagulation has so taken place, the coagulation liquid 5 starts wetting the surface 2 which was dry untilinow by diffusing through the strip 5;

The start of the regeneration process is aidedv .Beyond the device I0, the strip again passes onto the surface 2 and while so spread on it may thus be moistened with a fresh coagulation fluid and regenerated without being stretched, extended or shrunk, as 'a result of which, layers of exceedingly slight thickness, as an instance having a weight per square inch of less than 0.40 ounce, may be predetermined.

The device I Il while not necessarily positioned of the bath 5 is so illustrated in invention, but `at least should be positioned at a point where the coagulation fluid begins to pene` trate the strip or layer 5 to the surface 2.

If necessary the roller II, as shown in Fig..2 may be provided to guide the strip 5 as it passes from the device I back to the surface 2.

Tige strip which by now should be coagulated sulc ently so that it cannot be deformed any more, is then removed with the aid of the roller I2. As the surface 2 has been moistenedvwith coagulation fluid at least at the point 9, and fresh coagulation fluid supplied to the surface 2, the removal of the strip 5 at the roller I2 will take place very easily and safely, particularly as compared to the processes heretofore known. Consequently, there is no danger of the strip sticking to the surface 2 nor in being impaired or injured when being removed from the surface 2.

'I'he moisture which remains on the surface 2 after the removal of the strip, is wiped ofi.' by scr'aping means, such as the pivotally mounted scrapers I3 so that the surface 2 will be dry again after passing such scrapers I3. As a special precaution effectively to dry this surface 2, before returning to the nozzle 4, the remaining moisturev if any may be wiped of! or evaporated by warm air supplied by the blower- After the strip 5 is removed by the roller I2, it is passed through different treatment baths, washed and the like and finally dried. The device I0 shown in Figs. 3 and 4 comprises a main body 2| which is pivotally mounted on the shaft 22 or the like. At the end of this main body 2I which is removed from its pivotal point 22,

there is provided a flexible blade 24 preferably composed of metal which is placed in a slit 23 in the present instance and secured by screws 25. The blade 24 is mounted to press against the surface 2 and is ground in such a way that it lies in intimate engagement with-the surface 2 throughout its whole width.

Transversely through the main body 2|, there extends the supply chamber 26 which forms a channel to receive the coagulation liquid supplied thereto by any suitable means such as a pump or the like.

This chamber 26 may be used to supply any other liquid between the strip 5 and the surface 2. The quantity of the liquid so supplied will of course be controlled by the pump (not shown).

A large number of minute orifices such as 2l, 25 and 29 are provided to form communications between the chamber 26 and the inner or lower surface of the strip 5, the surface 2 and even the blade 24.

The device I0 preferably also is tapered at its end adjacent to its shaft 22 as shown and provided with a slit 30 and screws 3l to receive and secure the blade 32 preferably composed of rubber which intimately Vengages the surface 2.

'I'he blade 24 which constitutes the advance edge relative to the movement of the pouring base 3 effects the transfer of the strip 5 from the surface 2 to the back of the device III. The supply of liquid through the orifices 21 and 23 facilitates the transfer of the strip 5 onto the back of the device I0. The blade 32 guides the strip 5 back to the surface 2, so that throughout this path of movement the strip 5'is constantly supported, so that it may not acquire any strlations, streaks or drregularities.

The strip 5 while so advanced-on the back of the device I 0, the surface 2 is supplied with liquid through 'the orifices 28 and thereby moistened.

Thel mode of operation of this process comprises completing not only the coagulation upon the surface 2 but also` the subsequent reactions, for the period required completely to solidify the strip 5. During the main coagulation reaction, the pouring base 3 is dry but thereafter and that is just before arriving at the device I0 and the covered part beyond it, the pouring base 3 is moistened with coagulation fluid or with a similar suitable liquid. This process is particularly characterized by providing the device Ill which supplies a fresh reaction liquid between the strip 5 and the surface 2 and insures that the strip 5 at this time i`s not transported without an effective support and furthermoreA in that between the removing roller I2 and the pouring base 3, the surface 2 is freed of moisture and arrives in a dry condition at, and under the nozzle 4.

In the embodiment shown in Fig. 1, the device I0 is located above the level of the coagulation fluid 6, the guiding roller II of Fig. 2 dispensed with and the strip 5 preferably removed by the conveyory 33 extending around the rollers 34 and 35the roller 35 being disposed above the trough 35 into which the strip 5 is then advanced, from which the strip .5 is fed by any suitable means to one or more or other treatment baths and the like according to the process being practiced.

In the embodiment shown in Fig. 2, on the other hand, after the strip 5 is removed by the roller I2, it passes under the idler 3l and then\ over the roller 38 whereuponit is advanced down into the trough 39. l l

Preferably especially when the device Il is positioned below the level of the liquid 6 in order to insure maintaining the stripping blade24 in intimate engagement with the surface 2 of the base 3, the shaft 22 has fixed thereon a lever 40 to receive the weight 4I as shown to exercise a torque on the shaft 22 and in turn to press in the blade 24 into intimate engagement with the surface 2 of the base 3 as shown.

It is recognized that films derived from viscose as a base have heretofore been successfully produced. These films, however, always exceeded in weight 0.40 ounce per 1000 square inches. The thinnest films derived from viscose heretofore produced have ,a thickness corresponding to 0.80 ounce per 1000 square inches.

It is also recognized that films derived from cuprammonium as a base have heretofore been produced which had a thickness corresponding to 0.40 ounce or less per i000 square inches.

By means of the present invention, however,

films derived from viscose as a basehave for the first time been produced in thickness corresponding to 0.40 ounce or less.

Films derived from viscose as a base are clearly distinguishable in kind .from films derived from cu-prammonium as a base, not.only byk means the 1ike,.from viscose and the like cellulose solutions, in which a,viscous layer is spread directly lating liquid 'depositsand is then returned to furonto asupporting base without any unsupported intervening free space, the base is actuated to immerse |the layer into a coagulating bath, the so coagulated layer is removed and subjected to regenerating and other treatments, and in addition the supporting base isv freed from any coaguther' support the layer being poured, the steps which comprise freeing the layer from said base when'the coagulation fluid begins 'to penetrate the layer to said base, supporting the layer while tions consisting in pouring a viscous layer directly onto a'pouring base without any intervening unsupported free space, immersing the layer so supported into a coagulating bath for a period which is sufficient to permit the coagulating fiuid' to start penetrating the layer* to said support, then freeing the layer from the base, and supplying a fresh coagulating uid to the-inner face of the layer so freed. -and returning thelayer so freed to the pouring base andretaining the layer thereon until eectively coagulated.

2. The process of manufacturing strips and the like from viscose and the like cellulose solutions consisting in pouring a viscousV layer directly onto a supporting base without any un'- supported intervening free space, actuating'the fbase thereupon to immerse the layer into acoagulating bath, freeingthe layer from said base when the 'coagulation fluid begins to penetrate the layer to said base, supporting the layer while y' s0 being freed, supplying a coagulating fluid .to

'the inner face of the layer so freed, thereupon returningl the. layer to said base, and retaining the same so supported untilcoagulatedthroughout.

3. The process of manufacturing strips and the like from viscoseand the like cellulose solutions consisting in .pouring a viscous layer directly onto a supporting base without any un-4 supported intervening free space, actuating the base thereupon to immerse the layer'into a coagulating bath, freeing the layer from said base when the coagulation fluid begins to penetrate the layer to said base, supporting the layerl while so being freed away from said base, supplying a coagulating fluid to the inner face of the layer so freed, and returning the layer to saidbase and retaining the same so supported thereon until coagulated throughout.

6. In the process of manufacturing strips and the like, from viscose and thelike cellulose solui. tions, in which a viscous layer is spread directly onto a supporting base without any unsupported intervening free space, the base is actuated to immerse the layerinto a coagulating bath, 'and the so coagulated layer is removed and subjected to regenerating and other` treatments, the steps which comprise freeing the layer from said base when thecoagulation fluid begins to penetrate the layer to said base, supporting the layer while so being freed away from said base, supplying a coagulating fluid to the support and to the inner face-of the layer so freed, and returning the layer to said base and retaining the same so supported thereon until coagulated throughout.

7. In the processof manufacturing strips and the like, from viscose and the like cellulosesolutions, in which a viscous layer is spread directly onto a supporting base without any unsupported intervening free "space, the base is actuated to immerse the layer into a coagulating bath, the so coagulated layer is removed and subjected to regenerating and other treatments, and in addition the supporting base is freed from any coagulating'liquid deposits.' is then dried and returned to continue supporting the layer being spread,

the steps which comprise freeing the layer from said base when the coagulation -fluid begins to penetratev the layer to `said base, supporting the 'so-being freed, supplying a fresh supply of coagulating fluid to the support and to the unexposed face of Asaid layer when initiallyfreed -to` facilitate the coagulation action, returning the layer to said base, and retaining the same so supporte-d until coagulated throughout.

4. In the process of manufacturing strips and the like, from viscose and the'like cellulose solutions, in which a viscous layer is spread ydirectly onto a supporting base without any unsupported intervening free space, the base is actuated to immerse the layer into a coagulating bath, and

the so coagulated layer is removed and subjected to regenerating and other treatments, the steps which comprise freeing the layer from said base when the'coagulation f iuid begins to penetrate the layer to said base, supporting the layer while s`o being freed away from said base, supplying a coagulating fluid to the inner face of the layer so -freed, and returning the layer to said base and retaining the sameto supported thereon un- I til cnegulated throughout.

^ 5. In the process of`manufacturing strips and layer while so being freed away from said base, supplying a coagulating fluid to the supportand to the inner face of the layer so freed, and returning the layer to said base and retaining the same so 'supported thereon until coagulated throughout.-

' 8. The process of manufacturing strips and the like from viscoseI and the like cellulose solutions consisting in spreading a viscous layer directly onto a supporting base without any intervening unsupported free space, coagulating the` layer by immersing the same while supported on the base into a coagulating bath for a period which is sufficient to permit the coagulating. fluid to start penetrating the. layer to said support, de-

taching the`v layer from the base, transporting the detached layer at a distance removed'from .the base, thereupon returning the layer to the original supporting base, and retaining the sameso supported thereon until coagulated throughout.

9. The process4 of manufacturing strips and the like from viscose and the like cellulose solutions consisting in spreading a viscous layer 'di- -rectly onto a supporting base-without any 4intervening unsupported free space; coagulating Athe layer by immersing the same while supported on the base into a coagulating bath for a period which is sufeient to permit the coagulating uid to start penetrating the layer to said support, detaching the layer from the base, transporting the detached layer at a distance removed from the base, supplying further coagulating fluid to the inner face of the layer and to the supporting base, -thereupon returning the layer to the original supporting base, retaining the same so supported thereon until coagulated throughout,

and nally removing the thoroughly coagulated strip from the base.

10. A iiexible transparent and strong cellulose strip, regenerated from viscose, free from striations, streaks and irregularities having a weight per 1000 square inches of less than 0.40 ounce,

said strip being produced by spreading a viscose cellulose solution directly onto a supporting base, immersing the layer so supported into a coagulating bath for a period which is sufilcient to permit the coagulating fluid to start penetrating the layer to said support, then freeing the layer from'the base, supporting the layer while so being freed awaylfrom said base, and supplying a fresh coagulating fluid to the inner face of the layer so freed, returning the layer so freed to the original supporting base, 'retaining the layer thereon until effectively coagulated, and nally removing the solidied strip from the supporting base, regenerating, bleaching, washing and drying the strip in subsequent treatments. l

EMIL CZAPEK. 

